Contact Info

Quick Message

Stainless Steel piping products FAQs

Below you will find the frequently asked questions by customers regarding stainless steel piping products. Browse through and see if any of them answer a question you may have. For more information, please contact us for professional tech-supporting. You may also call us at 0086-13738731708 (24h).

Q: What grades of stainless steel pipes and fittings does walmi supply?

A: all T300 series austenitic stainless steel.

304/304L

316/316L

321/321H

310S

317L

S31803/S32205

S32750

904L

Q: Does Walmi offer cutting service for stainless steel pipe?

A: Yes. All pipes can be cut to the exact length of customer requirements.

Q: What is the Difference Between Tubing and Pipe?

A: Tubing and pipe may be used interchangeably in some instance, however, there are some differences when the material is ordered, the tolerance of stainless steel tubing and pipe is also different.

Tubing is typically ordered to outside diameter and wall thickness, however, it may also be ordered as OD & ID or ID and Wall Thickness. Although tubing has three dimensions (O.D., I.D. and wall thickness) only two may be specified with tolerances and the third is theoretical. Pipe is typically ordered using the Nominal Pipe Size (NPS) standard and by specifying a nominal diameter (pipe size) and schedule number (wall thickness). Also tubing is usually ordered and held to tighter and more stringent tolerances and specifications than pipe.

Q: What Does Gauge Mean?

A: The “gauge” of stainless steel refers to the thickness. Gauge is represented numerically. For stainless steel, as the gauge number increases the material thickness decreases. This means 14 gauge is thicker than 16 gauge.

Q: What is stainless steel?

A: Stainless steel is an iron-based alloy that contains more than 10 percent chromium. It is this element that reacts with the oxygen in the air to form a complex chrome-oxide surface layer that is invisible but strong enough to prevent further oxygen from “staining” (rusting) the surface.

Q: What is the "annealed" condition?

A: Stainless steel is usually sold in the “annealed” condition. It just means that the material is in the “soft” or annealed condition. The 300 series of stainless steels can not be hardened by heat treatment (like carbon steels) but can be hardened by cold working. This cold work can be eliminated by a heating treatment (annealing) that will restore the original soft condition.

Q: What’s function of pickling and passivation after heat treatment?

A: Pickling and passivation of stainless steel fabrications can be used to remove contaminants on the surface of the metal.

Pickling is used for contamination such as embedded iron. Passivation removes surface chemicals and other contaminates. The passivation process helps in the formation of a tenacious protective chromium oxide film. There are a number of specifications commonly governing stainless steel passivation.

Q: Is stainless steel magnetic?

A: Yes and no. The high nickel and chromium contents of the T300 austenitic series stainless steel contains nickel and does not have magnetic properties. All the ferrite, martensitic, and precipitation hardening grades, which does not contain nickel, is magnetic. However, the 300 series stainless steel can also become magnetic during the cold-working processes used to harden them.

Q: What does the "L" designation mean?

A: The L indicates low carbon grades, such as 304L, means that the carbon content is restricted to a MAXIMUM of 0.03% (normal levels are 0.08% max. and in some grades can be as high as 0.15% max.). The “L” grade material helps reduce the possibility of carbide precipitation forming during processes, so which is usually used where “welding” will be performed.

Q: What is Cold Working? (Cold Forming)

A: Cold working or work hardening is the process of strengthening a metal by deformation at temperatures below the recrystallization temperature. Any mechanical operation that creates permanent formation, such as bending, rolling, drawing performed at room temperature that increases the hardness strength of stainless steel. Cold working decreases mechanical properties of metal like elongation, reduction of area and impact values.

Q: What are the Characteristics of Stainless Steel?

A: Stainless steel’s non-corrosive characteristic gives it a long lifespan. With the addition of nickel, the material survives even longer and in several types of environments. By adding molybdenum and nitrogen, stainless gains improved pitting and crevice corrosion resistance. Stainless steel has a high strength-to-weight ratio even at high temperatures. Adding alloys to stainless steel helps it resist heat and scaling. Stainless steel is easy to clean because the surface is non-porous. It is well suited for medical and food-grade applications because it prevents the absorption of bacteria and germs. Stainless steel does not stain and can be polished to create an aesthetic appearance.

Q: Can stainless steel be "welded"?

A: YES. Stainless steel is easily welded, but the welding procedure is different than that used with carbon steel. The “filler” rod or electrode must be stainless steel.

Q: Can stainless steel be machined?

A: YES.

Q: Can stainless steel be used at very low and very high temperatures?

A:Yes. Stainless steel has excellent properties at both extremes of the temperature scale. Stainless steel can be used down to liquid nitrogen temperatures and up to about 980℃.

Q: Can Stainless steel be "hardened"?

A: YES. The 300 series stainless steel can be “hardened” BUT only by “work hardening.” That is by cold working the material, either by cold rolling down to lighter and lighter gauges, or by “drawing” through a die or other size altering operation. “Annealing” stainless steel will REMOVE the work hardening effect.

Q: Can stainless steel rust?

A: Yes. Stainless does not “rust” as you think of regular steel rusting with a red oxide on the surface that flakes off. Corrosion is generally caused by contaminants settling on the surface of the stainless steel.